Studies of large scale forest fuel supply systems.

The thesis reviews five papers dealing with large scale systems for production and supply of forest fuel. An attempt is made to discuss and generalise the results so as to draw such conclusions that can not be based on any single of those papers. The reviewed papers fall into two, fairly discrete groups. The first group (papers I, II and V) lies within the classical area of time and productivity studies. Papers I and II present a comparison of the conventional processing method of Scandianvian shortwood systems with a differentiated processing method, in which only sawlogs are processed at the stump while pulpwood and forest fuel are transported off the site as undelimbed tree sections. The development of a precise but demanding videogrammetric study method played an important role in these studies. Both motor manual and mechanised production systems were studied. For motor manual logging, differentiated processing is to be recommended for ergonomical, economical and efficiency reasons. For the mechanised shortwood systems included in the studies, differentiated processing did not have the same clear advantages, but may be recommendable in certain types of stands and conditions. The last paper describes a study investigating the influence of the operator on pay load size and productivity development in tree-section hauling. The results indicate that training of operators is essential when work tasks are changed. Training and experience are key factors for archieving the potential level of productivity. The second group of studies (papers III and IV) concern the forest fuel supply systems as a whole, from stump to heating plant. The studies are aimed at a comprehensive overview of the alternative systems employed. The systems analyses were performed from logistic and managerial perspectives and showed that the efficiency of the studied system could be sustaintially improved by fairly simple adaptations of planning and organisational development within the existing structure. Some rules of thumb to be considered in the construction of forest fuel supply systems may be concluded from these studies.